Construction projects that require installations across streams and other water resources are inherently problematic relative to issues of surface-water quality. Proper protocols must be followed for handling in-stream construction work to prevent suspended-solids release into the water body. This often involves the temporary isolation of the proposed crossing location by creating temporary dams immediately upstream and downstream of the construction crossing. These temporary isolation dams are typically constructed out of sand bags to create a relatively “clean” temporary barrier for flow. Once these barriers are in place, pumps or diversion channels can be installed to divert stream flow around the construction crossing location. When this bypass is in place, the construction at the crossing can take place. However, construction will usually create a suspended-solids slurry that must be evacuated from the crossing location in order to provide a dry, stable foundation for construction. The slurry is pumped out of the crossing pit and discharged away from the crossing location. This slurry can be a highly concentrated suspended-solids solution that will require treatment before it is discharged back into the stream. Conventional treatment approaches include using bags as filters. These bags may be constructed of porous material such as burlap or woven plastic material and are designed to be filled with a ballast such as sand, gravel, or wood chips so that the bags, when in place, may be filled further with the slurry/water mixture so that it slowly “bleeds” out or flows through the porous material, resulting in some degree of filtration and collection of solids onto the bag surface. These bags often clog very easily and are marginally successful in solids reduction with little removal of fine, colloidal solids associated with many clay soils. Accordingly, one of the objects of this invention is to provide a method and flow control system that improves the quality of water discharged into streams at construction sites by reducing the quantity of solids in the water. This is a dewatering process where high purity water is removed from the solids in a slurry.